This invention lies in the field of gas turbine engines for aircraft which produce reaction thrust by discharging a high velocity stream of gas from the exhaust nozzle of the gas turbine. This invention is directed to apparatus for varying the gas turbine exhaust nozzle exit area of high performance aircraft to optimize thrust for subsonic and supersonic flight regimes and which also incorporates means to effect thrust modulation and thrust reversal in flight or during ground roll. It is directed more particularly to a variable area divergent exhaust nozzle which is integrated with a target-type thrust reverser for use in conjunction with a convergent nozzle, the combination of which are relatively simple in construction and mechanization and are configured to obtain a high degree of forward thrust efficiency.
In the forward thrust mode, the nozzle system may be used for efficient subsonic cruise operation and efficient supersonic acceleration and dash operation. In the reverse thrust mode, the system may be used to produce superior aircraft deceleration capability to enhance Air Combat Maneuvering and to improve air-to-ground weapons delivery. In the modulated thrust mode, the system may be used for precise flight path control for formation flying and aerial refueling and as a high drag device to permit steep approach angles for landings while maintaining precise glide path control and a rapid full-thrust go-around capability. On the ground, the system may be used to produce superior deceleration capability to reduce landing ground roll distance and to modulate and reduce excessive taxi thrust inherent with some designs.
The usual prior art variable area convergent-divergent nozzle systems for use with augmented gas turbine engines achieve area modulation by use of complex multiple petal designs which split the nozzle into many segments of flaps and seals to attain area modulation. The large number of interleafing parts and complex actuating mechanisms contribute to a very expensive nozzle system which cannot be simply integrated with a thrust reversing apparatus.